Electron multiplier with replaceable rear section

Abstract

A segmented electron multiplier is disclosed with front and rear sections. The sections are specially designed so that the length of the rear section compared to the length of the front section is no less than 4:1. This permits multiple replacements of the rear section, after the multiplier wears out, without any unsatisfactory drop in the overall electrical gain produced by the repaired device. In the preferred embodiment, the front portion is a funnel having a tubular stem, and the rear portion is a straight tube with a cylindrical helical inner channel. The length-to-length split is 5:1, which theoretically permits up to six or seven replacements of the rear section before unsatisfactory gain occurs.

Having thus described the invention, what is claimed is: 
     
       1. A segmented, continuous dynode electron multiplier for producing electron gain, said multiplier comprising: a. a funneled inlet section with a tubular stem, said stem having a channel with a secondary electron emissive layer;   b. a tubular rear section that is removably connected to the stem, said rear section having a channel with a secondary electron emissive layer; and   c. wherein the ratio of the length of the tubular rear section to the length of the stem is no less than 4:1, whereby multiple replacements of the rear section can be made, after the rear section wears out, before unsatisfactory gain degradation occurs.   
     
     
       2. The segmented multiplier of claim 1 wherein the ratio is greater than 4:1. 
     
     
       3. The segmented multiplier of claim 1 wherein the ratio is substantially 5:1. 
     
     
       4. The segmented multiplier of claim 1 wherein the inlet and rear sections are removably connected, and the stem and rear sections are aligned with one another, by a fuse clip. 
     
     
       5. A segmented, continuous dynode electron multiplier for producing electron gain, said multiplier comprising: a. a funneled inlet section with a tubular stem, said stem having a channel with a secondary electron emissive layer;   b. a tubular rear section that is removably connected to the stem, said rear section having a channel with a secondary electron emissive layer;   c. a metal fuse clip that aligns and connects the sections, said clip having a flat base and two horseshoe clip springs, whereby the stem is mounted within one of the springs and the rear section is mounted in the other; and   d. wherein the ratio of the length of the tubular rear section to the length of the stem is no less than 4:1, whereby multiple replacements of the rear section can be made, after the rear section wears out, before unsatisfactory gain degradation occurs.   
     
     
       6. The segmented multiplier of claim 5 wherein the ratio is greater than 4:1. 
     
     
       7. The segmented multiplier of claim 5 wherein the ratio is greater than 5:1. 
     
     
       8. A segmented, continuous dynode electron multiplier for producing electron gain, said multiplier comprising: a. a funneled inlet section with a tubular stem, said stem having a channel with a secondary emissive layer;   b. a tubular rear section that is removably connected to the stem, said rear section having a channel with a secondary emissive layer;   c. a connecting means that aligns and removably connects the sections, whereby the stem is mounted within one portion of the means and the rear section is mounted in another in an end-to-end relationship; and   d. wherein the ratio of the length to the tubular rear section to the length of the stem is no less than 4:1, whereby multiple replacements of the rear section can be made, after the rear section wears out, before unsatisfactory gain degradation occurs.   
     
     
       9. The segmented multiplier of claim 8 wherein the ratio is greater than 4:1. 
     
     
       10. The segmented multiplier of claim 8 wherein the ratio is greater than 5:1.